A word from Machelle, the 'Hocus Pocus' costume creator:

from left it right... Whitney (Sarah), Gwen (Winifred), Machelle (Mary)
We made all of our costumes out of old dresses, spare fabric pieces, and black netting. Winifred had foam rollers to get her hair to do that and fake teeth she ordered online. Mary (me) used a styrofoam cup, wire hanger, and LOTS of black hairspray.